ARRL Propagation Bulletin ARLP031 (1999)

SB PROP @ ARL $ARLP031
ARLP031 Propagation de K7VVV
ZCZC AP31
QST de W1AW
Propagation Forecast Bulletin 31 ARLP031
From Tad Cook, K7VVV
Seattle, WA July 30, 1999
To all radio amateurs
SB PROP ARL ARLP031
ARLP031 Propagation de K7VVV
Sunspot numbers and solar flux took a big leap upward this week, and
the trend continues until the weekend. Average sunspot numbers were
up almost 55 points over last week, and average solar flux was up
almost 42 points. The high solar flux reading of 197.8 on Wednesday
continued on Thursday at 202.4. This is much higher than forecast
last week. Solar flux on Friday is predicted to be around 200, and
190 and 180 on Saturday and Sunday. Planetary A indices for Friday
through Sunday are predicted to be ten for all days.
Beyond the weekend, solar flux should drop to 170 around August 4,
160 by August 8, and 140 around August 12. Flux levels are expected
to be back above 200 by August 19 and possibly 210 around August 21.
By that date 10 meters should be quite exciting.
Many positive responses to last week's bulletin about the meaning of
the solar and geomagnetic indices, and among the mail was a tip from
K9MIF about http://hamradio-online.com/1998/jun/wwv.html, which was
created by KC7LVZ. This web page has some nice explanations for the
various solar numbers, and what they mean to hams. N6RT sent along
a pointer to http://dx.qsl.net/propagation, which he created to show
solar information from a number of sources in one handy location.
Scott Craig, WA4TTK has an update to his solar plotting program.
This freeware takes data directly from this bulletin and plots it on
your computer. If you aren't running it yet, now is a good time to
download it, because the data files have been updated through July
24. You can add to it by taking the data out of these bulletins,
which the program can do automatically. Go to
http://edge.net/~scraig/sol.htm for the download.
Sunspot numbers for July 22 through 28 were 127, 158, 173, 183, 150,
161 and 218 with a mean of 167.1. 10.7 cm flux was 152.8, 193.7,
184.2, 182.3, 172.4, 174.5 and 197.8, with a mean of 179.7, and
estimated planetary A indices were 24, 12, 12, 8, 7, 6 and 9, with a
mean of 11.1.
Path projections for this week are from the center of the contiguous
48 states of the USA.
To Europe, 80 meters 0200-0500z, 40 meters 0030-0600z, 30 meters
2330-0730z, 20 meters 2100-1200z (best 0200-0430z), 17 meters
1400-0230z (better toward the end of the period).
To Southern Africa, 80 meters 0130-0500z, 40 meters 0100-0500z, 30
meters 0000-0530z, 20 meters 2230-0630z, 17 meters 2100-0230z and
0500-0730z, 15 meters 1730-0200z (stronger toward the end of the
period) and 0530-0600z.
To the Caribbean, 80 meters 0100-1030z, 40 meters 2300-1200z, 30
meters all hours, best 0230-0900z, weakest 1530-1930z, 20 meters all
hours, best 0230-0700z, 17 meters 1300-0500z, 15 meters possibly
1600-2200z.
To South America, 80 meters 0130-1030z, 40 meters 0030-1030z, 30
meters 2330-1100z, 20 meters 2200-1230z (best 0200-1000z), 17 meters
all hours, best 0230-0800z, weakest 1630-1800z, 15 meters
1030-0700z, 12 meters 0200-0400z and 1400-0000z, best 1830-2000z, 10
meters possibly 1530-2200z.
To Australia, 80 meters 0700-1200z, 40 meters 0630-1230z, 30 meters
0600-1300z, 20 meters 0500-1430z, 17 meters 0400-1430z, 15 meters
0100-0900z, 12 meters 2030-0830z (stronger later in the period), 10
meters 2100-0100z and 0400-0500z.
To Japan, 80 meters 1030-1130z, 40 meters 0930-1200z, 30 meters
0830-1300z, 20 meters 0600-1530z, 17 meters all hours, best
0800-1330z, 15 meters 1300-0730z, best 1930-2200z, 12 meters
possibly 1800-0100z and 0330-0730z.
NNNN
/EX